National estimates for the percentage of 19 - 35 month old children who are up-to-date on recommended vaccines remain below the Healthy People 2020 goal. An important contributor to under-immunization is parental refusal or delay of childhood vaccines due to significant vaccine concerns. Evidence suggests pediatric providers are an important influence on parental vaccine decision-making and that their vaccine discussions with parents can increase vaccine acceptance. However, several parent- and provider-level barriers to improving the vaccine discussion exist, such as insufficient time to discuss parental vaccine concerns during health supervision visits, parental difficulty in disclosing vaccine concerns, and provider inaccuracy in identifying which parents have vaccine concerns. Consequently, parental vaccine concerns are often neglected and opportunities to improve vaccine uptake are missed. The primary goals of this project are to evaluate the effectiveness of an innovative intervention designed to address these barriers-the Screening for Hesitancy to Optimize Talk (SHOT) intervention-in improving provider-parent vaccine discussions and increasing vaccine acceptance. The SHOT intervention involves administering a validated parent-report measure, the Parent Attitudes about Childhood Vaccines (PACV) survey, to parents and communicating their score and item-specific responses to their child's provider before their child's 2 and 6 month health supervision visits. The PACV contains 15 questions regarding Health Belief Model concepts that influence parent vaccination behavior and has been shown to predict under-immunization. We hypothesize that using the PACV to solicit parental vaccine concerns and hesitancy status prior to health supervision visits in which vaccines are administered will improve providers' ability to adequately address parental vaccine concerns and increase parental vaccine acceptance. Our specific aims will be to (1) evaluate the impact of the SHOT intervention on a child's immunization status using a matched-pair, cluster randomized controlled trial design in which we assign 16 primary care clinics within the Group Health healthcare delivery system based in Seattle, WA to a control arm or the SHOT arm and enroll 160 vaccine-hesitant parents whose newborns receive health supervision at study clinics; (2) assess how parents' ratings of their vaccine discussions with their child's provider change as a function of the SHOT intervention; and (3) compare pre- and post-study perceptions of barriers to quality vaccine discussions with parents between providers in the SHOT and control arm. This R21 application addresses a significant public health problem-parental vaccine hesitancy and refusal-for which there are currently few well-designed and rigorously evaluated interventions. It will provide evidence for the feasibility and efficacy of administering the PACV in a primary care setting and will inform the design and evaluation of a future R01-funded multi-site randomized controlled trial.